Air carrier X radar vector below MVA received GPWS climb. System error.

Attributes
ACN	294040
Time
Date	199501
Day	Fri
Local Time Of Day	0001 To 0600
Place
Locale Reference	atc facility : roa
State Reference	VA
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Flight Conditions	Marginal
Light	Dawn
Aircraft 1
Controlling Facilities	tracon : roa
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other
Route In Use	enroute : direct enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 130 flight time total : 10000 flight time type : 500
ASRS Report	294040
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : published procedure other spatial deviation
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	controller : issued new clearance flight crew : exited adverse environment flight crew : took evasive action
Consequence	Other
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

X was on approach to runway 33 at roa for an ILS to this runway. ATIS visibility was 4 mi prevailing. I was advised by approach control that the roa tower was reporting 1 mi visibility. This was below minimums for ILS 33 roa, 1 1/4 mi required for this approach. (Aim procedures for visibility prevailing versus tower measurements.) I asked for vectors to the lda runway 6 at roa needing 1 mi visibility for this approach. I was at 5000 ft MSL and through the centerline for lda runway 6 heading south and east. I was given a turn west to parallel downwind the approach course for lda runway 6. This was about a 240 degree heading. At about 12-15 DME on the lda frequency of 111.1 for runway 6 at roa, I was turned to a heading for a right base about 330 degrees at 5000 ft MSL. Upon rolling out on base I received a GPWS terrain warning. The visibility was very marginal and I immediately began a climb to 5500 ft MSL advising the copilot to tell the controller. ATC was advised of our GPWS terrain warning immediately and we were cleared to 5500 ft MSL. I conformed to company procedures for unknown GPWS terrain pull up warnings with climbing maneuver. The approach to roa lda runway 6 was completed safely.

Original NASA ASRS Text

Title: ACR X RADAR VECTOR BELOW MVA RECEIVED GPWS CLB. SYS ERROR.

Narrative: X WAS ON APCH TO RWY 33 AT ROA FOR AN ILS TO THIS RWY. ATIS VISIBILITY WAS 4 MI PREVAILING. I WAS ADVISED BY APCH CTL THAT THE ROA TWR WAS RPTING 1 MI VISIBILITY. THIS WAS BELOW MINIMUMS FOR ILS 33 ROA, 1 1/4 MI REQUIRED FOR THIS APCH. (AIM PROCS FOR VISIBILITY PREVAILING VERSUS TWR MEASUREMENTS.) I ASKED FOR VECTORS TO THE LDA RWY 6 AT ROA NEEDING 1 MI VISIBILITY FOR THIS APCH. I WAS AT 5000 FT MSL AND THROUGH THE CTRLINE FOR LDA RWY 6 HDG S AND E. I WAS GIVEN A TURN W TO PARALLEL DOWNWIND THE APCH COURSE FOR LDA RWY 6. THIS WAS ABOUT A 240 DEG HDG. AT ABOUT 12-15 DME ON THE LDA FREQ OF 111.1 FOR RWY 6 AT ROA, I WAS TURNED TO A HDG FOR A R BASE ABOUT 330 DEGS AT 5000 FT MSL. UPON ROLLING OUT ON BASE I RECEIVED A GPWS TERRAIN WARNING. THE VISIBILITY WAS VERY MARGINAL AND I IMMEDIATELY BEGAN A CLB TO 5500 FT MSL ADVISING THE COPLT TO TELL THE CTLR. ATC WAS ADVISED OF OUR GPWS TERRAIN WARNING IMMEDIATELY AND WE WERE CLRED TO 5500 FT MSL. I CONFORMED TO COMPANY PROCS FOR UNKNOWN GPWS TERRAIN PULL UP WARNINGS WITH CLBING MANEUVER. THE APCH TO ROA LDA RWY 6 WAS COMPLETED SAFELY.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.